Java实现冒泡排序

冒泡排序

import java.util.Arrays;


public class BubbleSort {

    
    public int[] descSortV1(int[]  arr){
        int temp = 0;
        for (int i = 0; i < arr.length-1; i++) {
            for (int j = i+1; j < arr.length; j++) {
                if(arr[i] < arr[j]){
                    temp = arr[j];
                    arr[j] =  arr[i];
                    arr[i] = temp;
                }
            }
        }
        return arr;
    }

    
    public int[] descSortV2(int[]  arr){
        int temp = 0;
        boolean isSorted = true;
        for (int i = 0; i < arr.length-1; i++) {
            for (int j = 0; j < arr.length-i-1; j++) {
                if(arr[j] < arr[j+1]){
                    temp = arr[j];
                    arr[j] =  arr[j+1];
                    arr[j+1] = temp;
                    isSorted = false;
                }
            }
            if(isSorted){
                break;
            }
        }
        return arr;
    }

    
    public int[] descSortV3(int[]  arr){
        //记录最后一次交换的位置
        int lastExchangeIndex = 0;
        //无需数列的边界，每次比较只需要必到这里为止
        int sortBorder = arr.length-1;
        //临时变量
        int temp = 0;
        // 有序标记
        boolean isSorted = true;
        for (int i = 0; i < arr.length-1; i++) {
            for (int j = 0; j < sortBorder; j++) {
                if(arr[j] < arr[j+1]){
                    temp = arr[j];
                    arr[j] =  arr[j+1];
                    arr[j+1] = temp;
                    //有元素交换，所以不是有序的
                    isSorted = false;
                    //更新最后一次元素交换的位置
                    lastExchangeIndex = j;
                }
            }
            sortBorder = lastExchangeIndex;
            if(isSorted){
                break;
            }
        }
        return arr;
    }

    public static void main(String[] args) {
        BubbleSort bubbleSort = new BubbleSort();
        System.out.println(Arrays.toString(bubbleSort.descSortV1(new int[]{10,3,5,2,7,1})) );
        System.out.println(Arrays.toString(bubbleSort.descSortV1(new int[]{5,8,6,3,9,2,1,7})));
        System.out.println(Arrays.toString(bubbleSort.descSortV2(new int[]{10,3,5,2,7,1})) );
        System.out.println(Arrays.toString(bubbleSort.descSortV2(new int[]{5,8,6,3,9,2,1,7})));
        System.out.println(Arrays.toString(bubbleSort.descSortV3(new int[]{10,3,5,2,7,1})) );
        System.out.println(Arrays.toString(bubbleSort.descSortV3(new int[]{5,8,6,3,9,2,1,7})));
    }
}